Thats one way to market yourself, but not the only way. For example, consultancies don't come up with products people are willing to pay for. They are hired as a service to do work on a project, but they aren't selling things off the shelf. A software "consultancy" could operate in a similar way, where customers say "we need engineering labor to achieve our goals" and this agency comes in with the labor that develops the product to meet the companies needs.